Partitioning DDS Tapes

[dhaverstick]

Does anyone know how to partition 4mm DDS tapes in any flavor of UNIX besides HP-UX? My HP-UX box died and I have bunch of backup tapes with two partitions on them and I can't figure out how to read the second partition using other kinds of UNIX.

Thanks in advance,
Darren

 

[Annihilannic]

Can't you just mt fsf 1 to skip to the second 'file' on the tape? Or are partitions a different concept altogether?

Annihilannic.

 

[dhaverstick]

Partitioning a tape is like partitioning a hard drive. By having two partitions, I essentially have two volumes to write data to. It's a way to get two backups per tape, not have a lot of empty space, and save some money. Now if someone could just tell me how to access the second partition....

 

[KenCunningham]

Now if someone could just tell me how to access the second partition....

Now if someone could just tell me what equipment they're using for the restore, we might get somewhere...

Have you tried Annihilannic's suggestion? What would you use on the defunct HP system?

 

[motoslide]

Does your OS have a "tape" command?

Here's a snippet of the manpage for that command:

  tape -a 0 setpart /dev/nrStp0
  find /dir_A -print | cpio -oB > /dev/nrStp0
  tape -a 1 setpart /dev/nrStp0
  find /dir_B -print | cpio -oB > /dev/nrStp0

  The command tape -s -a 1 setpart positions the tape head at the beginning of
  partition 1 on the tape.

Another option (using Annihilannic's idea)

mt setpartition 0

setpartition
(SCSI  tapes)  Switch to the partition determined by count.  The default data partition of the tape is numbered  zero.  Switching partition  is available  only  if  enabled  for the device, the device supports multiple partitions, and the tape is  formatted with multiple partitions.


partseek
(SCSI tapes) The tape position is set to block count in the partition given by the argument after count. The default partition is zero.

"Proof that there is intelligent life in Oregon. Well, Life anyway.

 

[dhaverstick]

This is good info! I guess the other problem I have is making the correct device file to get to partition 1 of the tape. In HP-UX I used something like: mknod /dev/rmt/0mp c 54 0x201A12

to make the device file. I've tried that using UNIX Services for Windows (Interix?) to no avail. I can get to partition 0 using the default /dev/tape0 device file. Do I need to use different major and minor numbers to create the right device file?

 

[dhaverstick]

Sorry, Ken! The tape drive I'm using is an old HP C1520B 4mm SCSI DDS drive.

 

[elgrandeperro]

Okay, I've done tape operations lots of years, Annihillanic is correct.

On most Unixes, use the mt command to the NON rewind device to advance to the second file on the tape. If you use the
rewind device, /mt -f /dev/DEVICE fsf 1' it will seek to the start of 2nd file but then rewind the tape drive.

Tape device files on most unix only specify:
tape drive number
tape density or compression
rewind or non-rewind.
block or character mode

Now in the REAL old days, there were tape based filesystems that were really slow, and perhaps HPUX supported that concept. But I have only seen 1 person actually use this, and that was long ago.

gene